MS Visual C++ error while saving a file

When saving a file in MS Visual C++ IDE I get an error message:
“C:fdSdkSamplesEntityReadMe.txt” Cannot save file. The file may be in use by another application.
When I tried to saving the file again it erased all the changes I made and if I don’t save, it deleted the source file which is a bit annoying. I have an Antivirus installed with latest updates; Windows XP SP3 is also up to date.
I do not use this machine for any other purpose, so there is no chance of this application services being in use also.
Please let me know if anyone has a solution.
